[PATCH] KVM: arm/arm64: Stop leaking vcpu pid references

[Christoffer Dall]

On Wed, Jun 08, 2016 at 05:24:45PM +0100, James Morse wrote:
> kvm provides kvm_vcpu_uninit(), which amongst other things, releases the
> last reference to the struct pid of the task that was last running the vcpu.
> 
> On arm64 built with CONFIG_DEBUG_KMEMLEAK, starting a guest with kvmtool,
> then killing it with SIGKILL results (after some considerable time) in:
> > cat /sys/kernel/debug/kmemleak
> > unreferenced object 0xffff80007d5ea080 (size 128):
> >  comm "lkvm", pid 2025, jiffies 4294942645 (age 1107.776s)
> >  hex dump (first 32 bytes):
> >    01 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
> >    00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
> >  backtrace:
> >    [<ffff8000001b30ec>] create_object+0xfc/0x278
> >    [<ffff80000071da34>] kmemleak_alloc+0x34/0x70
> >    [<ffff80000019fa2c>] kmem_cache_alloc+0x16c/0x1d8
> >    [<ffff8000000d0474>] alloc_pid+0x34/0x4d0
> >    [<ffff8000000b5674>] copy_process.isra.6+0x79c/0x1338
> >    [<ffff8000000b633c>] _do_fork+0x74/0x320
> >    [<ffff8000000b66b0>] SyS_clone+0x18/0x20
> >    [<ffff800000085cb0>] el0_svc_naked+0x24/0x28
> >    [<ffffffffffffffff>] 0xffffffffffffffff
> 
> On x86 kvm_vcpu_uninit() is called on the path from kvm_arch_destroy_vm(),
> on arm no equivalent call is made. Add the call to kvm_arch_vcpu_free().
> 
> Signed-off-by: James Morse <james.morse at arm.com>
> Fixes: 749cf76c5a36 ("KVM: ARM: Initial skeleton to compile KVM support")
> Cc: <stable at vger.kernel.org> # 3.10+
> Acked-by: Marc Zyngier <marc.zyngier at arm.com>

Applied, thanks.

-Christoffer